The present invention relates to textured protein products, particularly meat analog fabricated food products prepared from food products formed from texturized protein.
In the past, much work has been done to provide satisfactory meat analog or simulated meats, from texturized protein particles.
A variety of prior art processes are known for "texturizing" vegetable protein, i.e., imparting to vegetable protein the chewy toughness and mouth-feel associated with meat, and assembling the texturized protein into familiar meat forms to provide meat analog products. For example, meat analog products can be made by processes involving fiber spinning or thermal plastic extrusion.
Fibrous textured protein products are prepared from proteins such as soy protein by forming a spinning solution from alkali solubilized protein and extruding the solution through a perforated die (spinnerette) into an acid (isoelectric) precipitating bath. The acidic bath sets the filaments or fibers as they emerge from the spinnerette. Thereafter, the fibers are collected for subsequent processing. The fibers, during the collection process, are usually stretched to orient the molecular structure of the fibers; thereafter, the fibers are assembled in "tows", bundles of individual fibers aligned in parallel fashion. Binding agents, coloring, fat and flavor can be added to the fiber tows and the entire fiber mass shaped to resemble familiar meat products. Details regarding the techniques are disclosed, for example, in U.S. Pat. Nos. 2,682,466, granted June 29, 1954 to Boyer; and 3,482,998, granted Dec. 9, 1969 to Carroll et al.
The thermal plastic extrusion process involves preparing a mixture of protein material, water, flavor and other ingredients and thereafter feeding the mixture into a cooker extruder wherein it is subjected to heat and pressure and subsequently extruded. The extrudate filament enters into a medium of reduced pressure (usually atmospheric) and expands to form a fibrous cellular structure. On rehydration, the fibrous filamentary texturized protein product can possess good appearance, bite and mouth feel. Details regarding thermal plastic extrusion techniques for the forming of textured protein meat analogs are disclosed, for example, in U.S. Pat. Nos. 3,488,770, granted Jan. 6, 1970 to Atkinson; and 3,496,858, granted Feb. 24, 1970 to Jenkins. With suitable binders, products similar to hamburger patties, meatballs, meat loaves and meat chunks can be formed. A variety of other processes are known for providing very suitable texturized proteins.
Textured proteins are generally obtained in the form of fiber pieces, fibrous extrudate filaments, or granules. These proteins must be bound together to form shaped meat or fish analog products, for example, beef chunk analogs, chicken analogs, hamburger patty analogs, meat loaf analogs and fish filet analogues. To hold proteins together, a suitable binder is required. To be acceptable, a suitable binder must present a reasonable bland or meat-compatible taste, bind effectively, heat set under mild conditions which will not adversely affect the protein particles. It must provide a product with an acceptable texture and mouthfeel when heat-set.
In the past, suitable binding materials for meat or fish analog products and natural extended meat products such as meat loaves and croquettes have included egg white. Egg white can be an excellent binding material, but the supply of egg white is limited and the cost is high. Attempts have been made heretofore to replace a portion of the egg white as the binding material in meat analog products. For example, U.S. Pat. No. 3,343,963, granted Sept. 26, 1967, to Kjelson discloses a three-component binder system comprising albumen, gluten and particulate defatted oilseed material; and U.S. Pat. No. 3,594,192, granted July 20, 1971 to Mullen et al., discloses a binder comprising egg white and a modified soy protein. Modified by treating soybean protein by raising this and on an aqueous dispersion of soybean protein to above about pH 9 and then reducing the pH to 5.5 to 8. While the treated soybean protein may exhibit improved binding properties, it is not a suitable binder as such. This binder still requires the presence of egg white.
There have been some fermentation based protein products, which when produced, are formed into long string-like masses by the microorganism itself. However, these materials must also be bound together with a binder in order to form useful fabricated food products.
Microbial cellular protein such as bacteria, yeasts, fungi and algae are rich in protein. Typical of the bio-synthetic processes for cultivating microorganisms, such as yeast, molds and bacteria, is the process described in U.S. Pat. No. 3,271,266 wherein microorganisms are grown in the presence of a petroleum fraction containing straight chain hydrocarbons, an aqueous nutrient medium and a gas containing free oxygen. Other suitable processes for the bio-synthetic production of microorganisms include the cultivation processes described in U.S. Pat. Nos. 3,268,413 and 3,384,491. The biosynthesis of protein, while providing a promising food source, has not become commercially acceptable in preparing protein for human consumption. One of the main reasons for lack of acceptance is the lack of texture inherent in these protein products. Single cell protein is generally produced as a wet paste and then dried. The dry powder, a flour-like material, lacks the texture and mouth feel necessary to make it an attractive food product. Further, when placed in water, the single cell protein becomes rapidly dispersed into single cells. Because of the extremely small particle size of the single cell protein (0.2-10 microns), the problem of texturizing these proteins cannot be easily overcome.
It would be desirable to provide a material which can be used to bind texturized protein or single cell protein which is available from an abundant source, has good nutrition, and flavor in addition to providing good binding as evidenced by good mouth feel and texture.